In modern painting installations for painting motor vehicle body components, rotary atomisers are usually used as application devices. To control the stream of paint, such rotary atomisers as a rule have a main needle valve which contains a slidable valve needle which is usually driven pneumatically as valve element.
What is disadvantageous about such a main needle valve is the fact that only a single stream of paint can be controlled. When changing paints, therefore, first of all the paint line has to be flushed and filled with the new paint, which is also referred to as reloading. This flushing and reloading takes a relatively long time, during which the rotary atomiser cannot be used for applying paint.
One further disadvantage of the known main needle valves is caused by the fact that the valve needle upon closing of the main needle valve is pressed into the valve seat in the direction of flow of the paint, as a result of which there may be a subsequent application of pressure on the paint, i.e. upon a closing operation spattering or dripping of paint may occur, which is undesirable.
With regard to the prior art, reference should also be made to DE 10 2013 006 219 A1, DE 10 2007 018 064 A1, DE 10 2010 056 071 A1, DE 195 24 853 A1 and DE 3 674 205.